Wavecor. Technical information. Zobel networks for impedance linearization.Useful in some cases for designing crossovers. Add in parallel with the driver an electronic circuit consisting of a resistor and a capacitor in series. This will compensate for the driver impedance rise caused by the voice coil inductance. Technical information: Suggested Zobel networks for Wavecor drivers In some speaker designs it is an advantage to use a so called Zobel network (figure on the right) to linearize the impedance of a drive unit. The effect of a correctly designed Zobel network is shown below on the impedance curve. Whether to use a separate network to equalize the high frequency impedance will depend on the crossover topology used, on personal design preferences, etc. A Zobel network is a series resistor-capacitor (Req- Ceq) network that is connected in parallel with a loudspeaker driver in order to neutralize the effects of the driver’s voice coil inductance Le (see note below about Le). If a Zobel, or other kinds of networks, are used for driver impedance linearization/modification, it is important that the network be connected right on the driver terminals, between the driver and the crossover. Note about Le: Normally the voice coil of a speaker driver is assumed to introduce a series inductance in the electrical equivalent circuit - most often called Le. If this assumption was true, the impedance curve of the drive would increase by exactly 6dB/octave at high frequencies. This is actually not the case as the impedance rise is closer to 3dB/octave. Read more about an alternative equivalent circuit here (305KB PDF). Although we are not dealing with a true inductance, the principle of neutralizing it using a resistor and a capacitor (zobel network) works rather well anyway. Driver model Req Ceq FR070WA01, 4 ohm * 8.2 ohm 5.6 uF FR070WA02, 8 ohm * 22 ohm 2.2 uF SW070WA01, 4 ohm 3.9 ohm 18 uF SW070WA02, 8 ohm 8.2 ohm 6.8 uF SW178WA01, 8 ohm 6.8 ohm 47 uF SW182BD01, 4 ohm 4.7 ohm 82 uF SW182BD02, 8 ohm 8.2 ohm 47 uF SW263WA01, 8 ohm 8.2 ohm 33 uF SW263WA03, 4 ohm 5.6 ohm 47 uF SW310WA01, 8 ohm 10 ohm 39 uF SW310WA02, 4 ohm 5.6 ohm 56 uF WF110WA01, 4 ohm 3.9 ohm 15 uF WF110WA02, 4 ohm 4.7 ohm 18 uF WF110WA03, 8 ohm 8.2 ohm 6.8 uF WF110WA04, 8 ohm 8.2 ohm 8.2 uF WF118WA01, 4 ohm 4.7 ohm 18 uF WF118WA02, 8 ohm 8.2 ohm 6.8 uF WF120BD01, 4 ohm * WF120BD02, 8 ohm * WF120BD03, 4 ohm * 10 ohm 10 uF WF120BD04, 8 ohm * 22 ohm 4.7 uF WF132TU01, 4 ohm 3.9 ohm 22 uF WF132TU02, 4 ohm 3.9 ohm 27 uF WF138WA01, 4 ohm 3.9 ohm 22 uF WF138WA02, 4 ohm 3.9 ohm 27 uF WF138WA03, 8 ohm 8.2 ohm 10 uF WF138WA04, 8 ohm 8.2 ohm 10 uF WF146WA01, 4 ohm 3.9 ohm 27 uF WF146WA02, 8 ohm 8.2 ohm 10 uF WF160WA01, 4 ohm 3.9 ohm 22 uF WF160WA02, 4 ohm 3.9 ohm 27 uF WF166TU01, 4 ohm 3.9 ohm 22 uF WF166TU02, 4 ohm 3.9 ohm 27 uF WF168WA01, 4 ohm 4.7 ohm 22 uF WF168WA02, 8 ohm 8.2 ohm 10 uF Drivers marked * have very slight impedance rise at high frequencies, typically because the center pole is covered by a copper cap (for the exact purpose of keeping impedance rise low). For these drivers the Zobel network is not a perfect impedance compensation but the shown Req and Ceq values are considered best compromise. Copyright© by Wavecor Ltd., Guangzhou, China. All rights reserved. Home Evaluation kits Newsletter Contact us OEM contact Company News Audio links Reviews & tests .